pituitrin and glycyl-histidyl-lysine

Gly-His-Lys, a tripeptide isolated from human plasma that increases the growth rate of many cells, stimulated in dose-dependent fashion the activity of phosphorylase a in isolated rat hepatocytes. Such effect was associated to increases in both IP3 production and [Ca++]i. Interestingly, these effects of Gly-His-Lys were antagonized by losartan, a nonpeptide angiotensin II receptor antagonist (AT1 selective), which suggested that these receptors were involved in its effect. Binding competition experiments using the radioligand [125I][Sar1-Ile8]angiotensin II clearly indicated that Gly-His-Lys interacts with AT1 receptors. It was also observed that other histidine-containing tripeptides were also capable of interacting with these receptors.

Topics: 1-Sarcosine-8-Isoleucine Angiotensin II; Amino Acid Sequence; Angiotensin Receptor Antagonists; Animals; Binding, Competitive; Biphenyl Compounds; Calcium; Cell Membrane; Dose-Response Relationship, Drug; Female; Growth Substances; Imidazoles; Inositol Phosphates; Liver; Losartan; Molecular Sequence Data; Oligopeptides; Phosphorylase a; Rats; Rats, Wistar; Receptors, Angiotensin; Signal Transduction; Tetrazoles; Vasopressins